“What we know at the outset is that Chris McDaniel won a sizable majority of the votes from Republicans who voted in the runoff,” Cruz said Monday night on the Mark Levin Show, a syndicated radio talk show with a Libertarian bent.

“But the D.C. machine spent hundreds of thousands of dollars urging some 30,000 to 40,000 partisan Democrats to vote to in the runoff, which changed the outcome.”

Citing “serious allegations” of voter fraud, Cruz said that “the only fair thing to do for the citizens of Mississippi is to investigate the allegations seriously and then prosecute anyone who was involved in criminal conduct.”

Peter Carr, a spokesman for the Justice Department’s Criminal Division, said that “at this time, we aren’t in a position to comment” on whether an inquiry is warranted.

“It would be abominable if Republicans were involved in voter fraud,” said Cruz, a leader of the tea party, which had placed high hopes that McDaniel would capture the seat that Cochran has held for six terms.

Even as Cruz lambasted the tactics of establishment Republicans, Cochran’s campaign said Monday night that the number of questionable votes found so far in an examination of election records was far fewer than Cochran’s 7,600-vote margin of victory. However, ballots had yet to be examined in Hinds County, home of Jackson, the most populous of the state’s 82 counties with about a quarter million residents. Hinds County also has among the lowest percentages of African Americans.

Ballots are still being reviewed in a number of other counties, but Austin Barbour, a senior adviser to Cochran’s campaign, said Monday that the Mississippi Republican Party’s Executive Committee had submitted certified results to Mississippi’s secretary of state.

The race between the 76-year-old Cochran and 41-year-old McDaniel, a conservative firebrand who attracted a host of political stars to his campaign events, was one of the fiercest ever in the state and crystallized the internecine battle over the future of the national Republican Party.

Cochran emphasized the hundreds of millions of dollars he has delivered to the state, one of the poorest in the nation, through his clout as a senior member of the Senate Appropriations Committee. McDaniel vowed to shrink the federal budget, stop pork-barrel politics and get the government out of people’s lives.

McDaniel narrowly won the June 3 primary, but fell just shy of the required majority of votes cast, forcing the runoff. Establishment Republicans, backed by the U.S. Chamber of Commerce and other business groups, unleashed an intense campaign to overcome McDaniel’s seemingly gathering momentum in the runoff campaign, courting African-Americans who vote Democratic but who also have benefited from the flow of dollars from Washington.

In Mississippi, Democrats are allowed to vote in a runoff if they haven't cast a Democratic primary ballot.

“I mean primaries are always rough and tumble,” Cruz said, “but the conduct of the Washington, D.C. machine in the Mississippi runoff was incredibly disappointing.”

“All of us want to grow the party, but what the D.C. machine did was not try to grow the party. The ads that they ran were racially charged false attacks and they were explicit promises to continue and expand the welfare state.

“And nobody has suggested that the Democrats who voted in the primary will actually vote Republican in the general election. Instead, they were just recruited to decide who the Republican nominee was, and that’s unprincipled and it’s wrong.”